The pictures are correct. With negative offset, the centerline of the wheel (red vertical line) is outboard of the hub. With positive offset, it is inboard (although the picture almost looks like 0 offset).
The pictures are correct. With negative offset, the centerline of the wheel (red vertical line) is outboard of the hub. With positive offset, it is inboard (although the picture almost looks like 0 offset).
OK I see what was confusing me. I assumed the hub was coming through the wheel center (the blob on the left). In reality, the wheel is being bolted on from the right. So outboard is further to the right as you stated.
I don't think that offset diagram does a very good job explaining the differences. This is much more clear.
It's called Positive Offset because it adds to the backspacing. A Negative Offset takes away from the backspacing.
My rims are 17x9 and have a -12 offset. I had 285/70s and I replaced them with 265/70s. Gas mileage went up by 1mpg, and turning is a lot easier. It also shaved 10lbs off each tire. The rims came on the van, I wouldn't have picked them otherwise. IMHO a 17x8 rim with a little less offset would be better. The "deep dish" shape of this rim has given multiple installers difficulty.
That is a much better diagram, Vermonster, thanks for posting. For some reason I need a constant reminder of how this works. Maybe this one will stick.
That is a much better diagram, Vermonster, thanks for posting. For some reason I need a constant reminder of how this works. Maybe this one will stick.
I agree for me at least most of the confusion was in identifying what in this picture is marked "street side".
I'm still in the middle of a van build (which at the moment is a complete overhaul of the F/R disk brakes) but here is a mockup (standing in front of the stock wheels) of the American racing wheel I bought circa 1999.
The Wheels are AR-166 17x8 with (+) 12 Offset. I was happy to see the weight rating at 3100 lbs. I'm probably going to run the 265/70-17 E-rated tires although there are 255/60R-17 tires mounted on the wheels.
So this is consistent with the fact that a positive offset moves the wheel inboard. The 12mm positive offset will keep the wider by 1" (17x8" vs 16x7") wheel on the centerline.
For reference, the following are the relevant tire sizes for stock and what I swapped out for a SUV tire on my 1997 E-350 RB and a 10 Ply for the 2000 E-350 XLT
Height Width
STOCK 225-75-16 29.3 8.9
225 Upgrade255-60-17 29.05 10
STOCK 245-75-16 30.5 9.6
245 10 ply upgrade 265-70-17 31.6 10.4
VanDeisels tire 265-65r17 is
30.6" and 10.4" which is closer to the Stock 245-75 than the 70 series.
Ended up putting a 3" coil spacer, method wheels NV 305s (17x8.5, 0 offset and 4.75 backspace). Cooper AT3 LTs (265 70R17).
No rubbing however without the spacer it may have some rubbing, at least on my van. I still trimmed a little bit off the fender and plastic under the bumper. It would likely rub a little in one spot, only if I wasn't on level ground and had the wheels slightly turned.
Simple solution for a few hours work, and only a hundred bucks. Images attached.
PigPen
Vandiesel II
Linear Mode
